Much of the slowness of a website's downloading is due to the
presence of non-optimized graphics. GIF files are often used as
designed graphics, since this graphic format offers lossless
compression of images. Images that contain large areas of similar
colors will compress very well in GIF format, with no loss of
image quality. In contrast, JPEG, although it offers superior
compression ratios, suffers significant distortion at high
compression ratios, especially in images that have areas of high
contrast. Below are some images from some common search engines
compared to optimized, 216 web "color-safe" GIF files
reduced through reduction in the number of colors in Adobe
Photoshop. Click here for a tutorial on how to do this.

Theirs

Mine

Saving
(%)

2330
bytes

2189
bytes

6

916
bytes

498
bytes

46

1518
bytes

751
bytes

51

2643
bytes

1394
bytes

47

2229
bytes

1057
bytes

53

5265
bytes

gif
3212 bytes/2317 bytes
jpg

39

There is a site on the web that will reduce the sizes of your
images for free. Check out GIF
Lube. This site reduces both GIF and JPEG images (and can
convert between the two). The best Windows-based program I have
seen for reduction of JPEG images is CyberView Image
(demo is available online). This program allows you to rapidly
reduce image sizes with real-time display of reduced images.
Sliders or numeric entry allow you to change image sizes while
comparing their original appearance with the appearance of the
reduced image in both 24-bit and 8-bit mode simultaneously. Adobe's ImageReady pales in
comparison and costs considerably more.